Device for folding a web of material

ABSTRACT

An apparatus and method for producing a zig-zag folded filter element from a web of material ( 18 ), which is supplied through a feeding device to a stamping unit ( 10 ). To define the folding line, the stamping unit is fitted with an anvil roll ( 21 ) and a stamping die ( 24 ), the stamping unit being ultrasound activated and thereby improving the stamping operation.

BACKGROUND OF THE INVENTION

The invention relates to a device for folding a web of material.

U.S. Pat. No. 4,778,441 discloses an apparatus for folding a web ofmaterial. It consists essentially of an embossing roller which hasconcave and convex embossing elements as well as a matching counterroller. The paper to be embossed is guided between the two rollers.

Also disclosed in German OS 42 01 288 is a method and a machine forproducing pleats on paper, filter material or other such media. Thismethod also operates with a pair of notched rollers with indentingknives and anvils. Variable pleating can be produced by controlling themaccordingly.

A device which produces zig-zag folded filter elements is disclosed inU.S. Pat. No. 3,514,354. Here two star rollers are provided which embossand simultaneously fold the paper. Conveyor belts follow the starrollers to guide the pleated element into a shaping apparatus.

A disadvantage in the known embossing or pleating devices is that, insome of the materials to be processed, the embossing action is notsufficient to achieve a precise folded edge. It is especiallydisadvantageous that mechanical embossing by means of cylinders above acertain maximum speed results in poorer results as regards the embossingaction.

SUMMARY OF THE INVENTION

The invention therefore is addressed to the problem of avoiding theaforementioned disadvantages and providing a device for folding a web ofmaterial, which will achieve a high folding output and even in the caseof different materials will emboss them sufficiently to enable them tobe pleated.

This object is achieved by the invention described and claimedhereinafter.

It is known to perform a welding of laminated materials or nonwovenmaterials by ultrasound. It is also known to cut nonwoven materials orpaper by the ultrasound method. In the case of the method of theinvention, however, neither a cutting process nor a welding process iscarried out.

The substantial advantage of the invention is that supporting theembossing action with ultrasound improves the embossing action andshorter cycle times are achieved. By the input of energy by ultrasound,especially when synthetic fiber nonwoven materials are used,plastification is produced in the area of the fold line by the heat thatis produced.

It is possible, of course, to provide vibrations of other frequenciesinstead of ultrasound, or to directly bring about heating in the area ofthe fold line by means of heating elements.

An advantage of the use of ultrasound is also to be seen in the factthat is can be applied precisely at the desired position. Energyconsumption is thus low, and the amount of energy applied can be verywell controlled.

In accordance with one embodiment of the invention the embossing unitcomprises at least one anvil roller with an appropriately designed shapeand a sonotrode. This sonotrode is a part of an oscillating structurewith which the necessary energy can be applied to and act upon the webof material.

In another embodiment of the device, two embossing units are to be used.With these the material web can be embossed on both sides and a zig-zagfolded element can be formed. After the material is provided with theembossing, it passes on to a receiving unit or set-up unit. Here thepleating is performed by the fact that, for example, the web of materialis introduced into revolving spindles. These spindles permit a preciseestablishment of the spacing between folds.

An advantageous embodiment of the invention envisions making the anvilrolls or the sonotrodes modular, so that they can be quickly exchangedand an adaptation to the desired embossing structure will be very easyto achieve. A method for producing a pleated element provides, accordingto the invention, for feeding a web of material through a feeder to anembossing unit. Ultrasound is simultaneously applied to the embossingunit to assist the embossing action. With this method it is possible toproduce a filter element from different materials, especially also fromsynthetic nonwoven material, which can be produced in an economicalmanner.

In another embodiment of the invention, a synthetic resin elementcomposed of active carbon or doped with active carbon is embossed, thusproducing a filter element which in addition to particles, also absorbsair pollutants and gases.

These and other features of preferred embodiments of the invention willbe found not only in the claims but also in the description and thedrawings, it being possible for the individual features to be realizedindividually or together in the form of sub-combinations in embodimentsof the invention and in other fields, and may represent advantageous andindependently patentable embodiments for which protection is herebyclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in further detail with reference toworking embodiments.

FIG. 1 shows a schematic layout of a device for folding a web ofmaterial,

FIG. 2 shows a schematic layout of another working embodiment of adevice for folding a web of material, and

FIG. 3 shows a detail view of a sonotrode.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the schematic diagram of the device in FIG. 1 an endless web 1 offilter material is shown. This is initially embossed in an embossingstation 10. The embossing station 10 is comprised of two anvil rolls 13and 14 which are equipped with embossing punches 15 and anvils 16. Thefilter material web 1 unwound from a roll 17 is thereby provided onalternating sides with a crease. The web of filter material passes fromthe embossing station 10 into the sphere of influence of a foldingstation 11, namely between two cogbelts 2 a and 2 b which fold theembossed web 1 in a defined manner. After the cogbelts the pleated web 1is conveyed in a defined manner in a worm screw 3. This worm screw 3 hasa variable pitch and can gather the pleated material together with acertain spacing between pleats. At the end a severing device 12separates the individual filter elements which are delivered by acomb-like element 6 to a transfer station 5. The embossing punches 15arranged on the embossing rollers 13 and 14 are each provided with asonotrode or are constructed in the form of sonotrodes and are excitedby an ultrasound generator. The sonotrode or the embossing punch thusproduces—through a friction effect and local heating—a plastification ofthe web composed of a nonwoven material and hence a contourcorresponding to a rippled profile.

FIG. 2 shows a schematic illustration of an apparatus which is a variantof the apparatus shown in FIG. 1. A web 18 of filter material isconveyed from a roll 19 to an embossing module 20. This embossing moduleis comprised of anvil roller 21 and anvil roller 22, as well as thesonotrodes 23 and 24 as part of a so-called oscillating structure. Asthe web passes through it, the sonotrodes emboss it at the intendedplaces, so that thereafter a fold is formed in the area 25. In order todefine the pleat spacing, two spindles 26 and 27 are provided, intowhich the web passes. These spindles have a diminishing pitch, so thatthe distance between pleats decreases in the direction of the arrow 28.After the final distance between pleats is established at the right-handend of the spindles, the web is transferred to two conveyor belts 29 and30. These conveyor belts carry the filter material web to a packagingand cutting apparatus, not shown here.

FIG. 3 shows on an enlarged scale the principle of the ultrasound-aidedembossing. Here are represented a sonotrode 24 and the anvil roller oranvil 21 through which the filter material web 18 is moved. During thetransport of the filter material, the application of ultrasound at thetip 31 of the sonotrode 24 causes a brief heating of the web within adefined area and thus leads to a permanent deformation. This permanentdeformation forms the crease locations 32. The size of the gap betweenthe sonotrode and the embossing roller 21 can be made variable and thuscan be optimally adapted to the web of filter material. It is alsopossible to emboss material coated with active carbon or material dopedwith active carbon. Here, again, the variability as regards theembossing depth is advantageous, especially when materials are used inwhich active carbon is embedded in a kind of multi-layer arrangement anddamage to these layers must be avoided.

The steps in the process of manufacturing a pleated filter element are:

The weakening of the material with the aid of ultrasound and thus alsothe simultaneous warming of the material,

thereafter the setting up of the filter material web in spindles orconveyor belts,

and then the fixing of the filter element by appropriate known measuressuch as beads of glue, side strips, or the like.

If a material doped with active carbon is used, the ultrasound processmakes it possible to reduce the size of the active carbon particles atthe crease. This has the advantage on the one hand that damage to thematerial is avoided and on the other hand that the crease location canbe very accurately defined even when active carbon particles are used.

It is advantageous to adjust the ultrasound action and thus the warmingof the material at the crease location so that, in the case of apolyester nonwoven material, a localized warming of about 110 to 120° C.occurs. This heating above the glass transition temperature results in alasting deformation, while the crease nevertheless remains plastic.

What is claimed is:
 1. An apparatus for folding a web of material, saidapparatus comprising a web feeder for feeding the web of material, atleast one embossing unit for defining fold lines on the web of material,and at least one sonotrode associated with the at least one embossingunit for applying ultrasound to the web to assist an embossing action ofthe embossing unit, wherein the at least one embossing unit comprises ananvil roller having an embossing contour and an embossing punch orknife, wherein said embossing punch or knife is constructed as asonotrode, said apparatus further comprising a set-up unit following theembossing unit, said set up unit comprising two parallel cogbelts forreceiving the embossed web between them and folding the web along theembossed fold lines to form a zig-zag folded filter element from thematerial web.
 2. An apparatus according to claim 1, comprising first andsecond embossing units, said first embossing unit embossing the web ofmaterial from one side, and said second embossing unit embossing the webof material from the opposite side, and wherein ultrasound is applied toboth embossing units.
 3. An apparatus according to claim 1, wherein atleast one of the anvil roller and the sonotrode is modularlyexchangeable.
 4. A method for producing a zig-zag folded filter elementfrom a web of material, said method comprising the steps of: feeding theweb of material to an embossing unit comprising at least one anvilroller and at least one embossing punch; embossing the web of materialin the embossing unit to define fold lines on the web of material; andapplying ultrasound to the embossing unit to support the embossing; saidmethod further comprising the steps of receiving the embossed web in aset-up unit comprising two parallel cogbelts and folding the web ofmaterial between said cogbelts in the set-up unit along the embossedfold lines to form a zig-zag folded filter element from the web ofmaterial.
 5. A method according to claim 4, wherein said web of materialis selected from the group consisting of paper, synthetic fiber nonwovenwebs, and synthetic resin elements doped with active carbon.